Reduce dependencies

[JingMatrix]

These commits will use system-wise libraries for mupdf, sqlite3 and utf8.
I tested it on my Ubuntu machine, not able to test for windows.

[JingMatrix]

I removed git-submodules, so the above build release won't pass.
Please tell on Windows or Mac to see if it works @ahrm .

[JingMatrix]

Or you can keep this pull-request open, (or you can create a new branch), to simplify building process for linux users.

[ahrm]

I am hesitant to accept changes that modify dependencies because getting them working in multiple operating systems was a nightmare.

[JingMatrix]

If I guess correctly, most dependencies problem comes from Windows instead of Mac, is that right?
Personally, I would suggest using CMake buiding system to improve this problem.

[ahrm]

Actually windows was quite easy. The main problem is various linux distributions and minor package difference between them.

[JingMatrix]

Could you give some expamles for your comments on various linux distributions? For exmaple, are there some related issues in the list?
Because I am really not convinced of this.

[ahrm]

For example ubuntu 18.04 LTS has an outdated version of mupdf that doesn't work with sioyek so we have to compile mupdf from source but then sometimes the libharfbuzz package from the system clashes with the libharfbuzz in mupdf source code and causes a hard crash, but if we don't install libharfbuzz there are problems for users who want to use their system's mupdf (there are multiple github issues about that). Most distributions don't need to explicitly install gumbo-parser because it is included in the mupdf package but some do. The name of some packages are different in different distributions, etc. etc.

I am hesitant to accept changes that change dependencies unless you explicitly test in on following systems:

• Windows 10+
• MacOS latest version
• Ubuntu 18.04 LTS and 22.04 LTS
• Archlinux

But your change for column handling in synctex is good, why don't you make a pull request without changing the dependencies?

[JingMatrix]

Well, my personal opinion is that we should use CMake build system to explicitly require the dependencies versions.
Providing (common) dependencies, such as mupdf, is the task of users instead of maintainers.
Usually, I believed that we need a sub-module only when we have a modified fork for our purpose.
This is just my personal ideas from experience, you may think differently.
For long-term maintenance, I strongly recommand so.

I am on Ubuntu 22.10, and it passed the compilation and works smoothly.
I don't use Windows 10, no way for me to test it.

With a copy of synctex in the repo for me is not a good idea.
I made this pull-request because the old version of synctex isn't working on my computer. So I turned to the latest version.

I will cherry pick the synctex and send a pull-request for it.